The LA463 and LA524 are very similar in specs so I suspect there will not be a noticeable difference between the two in actual use.
Since the LA463 fits the new machines and is so close in specs to the LA524, I'm not sure why Kubota introduced the 524.
Can anyone comment on this?

A Kubota salesman told me that the 66" QD bucket, due to being further away from the lift arms, lowers the max lift and breakout weights. He also said that the QD hook plates and levered pins are wear items that need to be watched.
Can anyone shed some light on this?

I went with the 60" pin on bucket on my L3800(LA524), because I don't need to take the bucket off. I can remove the whole FEL in about 5 minutes and do that for mowing. If I need forks, I'll make a set that fits on the bucket.

I went for the 66" QD bucket on the L3200 - mostly because that is what the dealer was stocking. As bluegill pointed out, you can remove the whole FEL in 5 minutes. Why bother with just the bucket? I've had the FEL off several times for mowing and tilling - never just the bucket.
If you are a jack welder and have a need for some other front ornament, the QD would be a better choice; you can pick up the skid steer frame cheap on ebay and make whatever you want. There are also lots of available attachments. And the bucket is a bit wider. If you add things to the bucket it keeps stretching out farther and farther in front, and becomes unwieldly.
If I had it to do over, I'd probably go for the pinned bucket. It will pry out more, although that has not been an issue - I can dig out 700-800lb rocks with ease. It is a bit narrower, which gives you a bit more maneuverability in tight spaces. I don't have any long term plans to change what is in front. 6" less payload isn't a particular issue. And if you are a jack welder it is not all that hard to make pin brackets...

This has been bothering me ever since I wrote my first reply. I have added spacers to my rear wheels, so they are 66" wide. When you are working with the loader, it is nice to have the bucket as wide as the tractor or you end up driving over the edge of your cut path, which makes the tractor uneven and the loader cut along with it.
I also have noted several times that the loader sticks our too far in front with the skid steer attachment. Awkward.
So for me, I think the ideal would be a 66" pin-on bucket. Kubota is pretty tight with their specs, so I guess to buy something you have to go to the lot with a tape measure and find out what will fit, then try to find it used or surplus - nobody can afford to just buy one at the dealer. If you are buying the tractor new, maybe you can force the dealer to choke up something that works.
Probably I will follow my own advice and use my jack welding skills to modify my QA bucket for pins, and set the skid steer attachment in the corner awaiting something I might just have to have that uses it.
The bottom line for me would be pin-on. If you plan ever to make the wheels wider than 60", find a bucket that fits and is the proper width.

I have the QC on my L3200. I have the standard 66" bucket, as well as a unused HD 60" Kubota bucket with a bolt on cutting edge. When I bought my L3200, I was for some reason convinced that the 66" bucket was just too big. Now I can see a LD 84" bucket or a I Beam attatched to a QC for back grading in my future.

I will never own another pin on type again unles it is a dedicated to one purpose machine. But then, I do switch between the bucket, forks and trailer mover a bit.

I also load a 5 yard dump truck, so the extra reach with the QC attatchment is handy. (yes, I have to build up a temporary ramp with whatever I am hauling to have enough lift height)